15W-40 Engine Oil Research Articles

Friction and wear characterization of sintered low alloyed chromium steels for structural components

► Lower and upper bounds for IRG wear transition diagram of sintered low alloyed chromium steels defined. ► One-hour gas nitriding of sintered low alloyed chromium steels rise onset to scuffing to over 1000 MPa. Sintered and sintered/gas nitrided cylinders made of low alloyed chromium steel Astaloy CrL + 0.45 C at 7.25 g/cm 3 density, have been tested for scuffing resistance and wear rate in a crossed cylinders test setup lubricated with a commercial SAE 10W40 engine oil at 90 °C. The results show large potential of 1 h gas nitriding of the sintered chromium steel cylinders. The nitrided cylinders experienced safe wear at 1000 MPa and scuffing at 1100 MPa at 2.5 m/s. At 0.5 and 0.1 m/s at least up to 800 MPa the wear was mild, as sintered chromium cylinders showed scuffing at pressure lower than 320 MPa and limited wear at 0.5 and 0.1 m/s.

Ionic Liquids as Novel Lubricants and Additives for Diesel Engine Applications

The lubricating properties of two ionic liquids (ILs) with the same anion but different cations, one ammonium IL [C8H17]3NH.Tf2N and one imidazolium IL C10mim.Tf2N, were evaluated both in neat form and as oil additives. Experiments were conducted using a standardized reciprocating sliding test with a segment of a Cr-plated diesel engine piston ring against a gray cast iron flat specimen. The cast iron surface was prepared with simulated honing marks as on a typical internal combustion engine cylinder liner. The selected ILs were benchmarked against conventional hydrocarbon oils. Substantial friction and wear reductions, up to 55% and 34%, respectively, were achieved for the neat ILs compared to a fully formulated 15W40 engine oil. Adding 5 vol% ILs into mineral oil has demonstrated significant improvement in the lubricity. One blend even outperformed the 15W40 engine oil with 9% lower friction and 34% less wear. Lubrication regime modeling, worn surface morphology examination, and surface chemical analysis were conducted to help understand the lubricating mechanisms for ILs. Results suggest great potential for using ionic liquids as base lubricants or lubricant additives for diesel engine applications.

Thermal characteristics of aluminum nanoparticles and oilcloths

Exothermic behavior of aluminum nanoparticles (ANP) in aqueous medium of various pH values and oilcloths (OC) composed of linseed oil, SAE 10W-40 engine oil, or SAE 20W-50 engine oil in cotton or nylon was studied. The experimental results revealed that for ANP hydrolysis, a deviation of pH value from 7 yielded a decrease in onset temperature ( T onset), peak temperature, no return temperature, self-accelerating decomposition temperature, time to T onset, time to maximum rate (TMR ad), and activation energy. Also, reaction order and frequency factor increased as pH value deviating from 7. For decomposition of oily materials, T onset of OC was lower than that of pure oil, suggesting that cotton and nylon enhanced the combustibility of the three oils. Besides, total enthalpy of OC was larger than that of the corresponding pure oil. Nylon-based OC produced larger total enthalpy than cotton-based OC, while the latter yielded shorter oxidative induction time (OIT) than the former. Moreover, reasonable discrepancy between experimentally determined OIT and theoretically estimated TMR ad was obtained. Hydrolysis of damped ANP and decomposition of OC could be derived from heat accumulation, leading to release of a considerable amount of thermal energy at relatively low T onset.

Super low friction of DLC applied to engine cam follower lubricated with ester-containing oil

This paper presents a material combination that reduces the friction coefficient markedly to a superlow friction regime (below 0.01) under boundary lubrication. A state approaching superlubricity was obtained by sliding hardened steel pins on a hydrogen-free diamond-like carbon (DLC) film (ta-C) lubricated with a poly-alpha-olefin (PAO) oil containing 1 mass% of an ester additive. This ta-C/steel material combination showed a superlow friction coefficient of 0.006 at a sliding speed of 0.1 m/s. A hydrogencontaining DLC coating/steel combination also showed a lower friction coefficient in air than a steel/steel combination, 0.1 vs. 0.8, but no large reduction was observed when the sliding surfaces were lubricated with ordinary 5W-30 engine oil and the PAO oil containing an ester additive. The friction coefficient of the hydrogen containing DLC/steel combination lubricated with the PAO containing an ester additive was above 0.05. On the other hand, the superlow friction performance demonstrates that the rolling contact friction level of needle roller bearings can be obtained in sliding contact under a boundary lubrication condition. It is planned to apply this advanced DLC coating technology to valve lifters lubricated with a newly formulated engine oil in actual mass-produced gasoline engines. A larger friction reduction of more than 45% is expected to be obtained at an engine speed of 2000 rpm.

Health effects of subchronic exposure to diesel-water-methanol emulsion emission

The U.S. Environmental Protection Agency's National Ambient Air Quality Standards for ozone and particulate matter (PM) require urban non-attainment areas to implement pollution-reduction strategies for anthropogenic source emissions. The type of fuel shown to decrease combustion emissions components versus traditional diesel fuel, is the diesel emulsion. The Lubrizol Corporation, in conjunction with Lovelace Respiratory Research Institute and several subcontracting laboratories, recently conducted a health assessment of the combustion emissions of PuriNOx diesel fuel emulsion (diesel-water-methanol) in rodents. Combustion emissions from either of two, 2002 model Cummins 5.9L ISB engines, were diluted with charcoal-filtered air to exposure concentrations of 125, 250 and 500 microg total PM/m3. The engines were operated on a continuous, repeating, heavy-duty certification cycle (U.S. Code of Federal Regulations, Title 40, Chapter I) using Rotella-T 15W-40 engine oil. Nitrogen oxide (NO) and PM were reduced when engines were operated on PuriNOx versus California Air Resources Board diesel fuel under these conditions. Male and female F344 rats were housed in Hazleton H2000 exposure chambers and exposed to exhaust atmospheres 6 h/day, five days/week for the first 11 weeks and seven days/week thereafter. Exposures ranged from 61 to 73 days depending on the treatment group. Indicators of general toxicity (body weight, organ weight, clinical pathology and histopathology), neurotoxicity (glial fibrillary acidic protein assay), genotoxicity (Ames assay, micronucleus, sister chromatid exchange), and reproduction and development were measured. Overall, effects observed were mild. Emulsion combustion emissions were not associated with neurotoxicity, reproductive/developmental toxicity, or in vivo genotoxicity. Small decreases in serum cholesterol in the 500-microg/m3 exposure group were observed. PM accumulation within alveolar macrophages was evident in all exposure groups. The latter findings are consistent with normal physiological responses to particle inhalation. Other statistically significant effects were present in some measured parameters of other exposed groups, but were not clearly attributed to emissions exposure. Positive mutagenic responses in several strains of Salmonella typhimurium were observed subsequent to treatment with emulsion emissions subfractions. Based on the cholesterol results, it can be concluded that the 250-microg/m3 exposure level was the no observed effect level. In general, biological findings in exposed rats and bacteria were consistent with exposure to petroleum diesel exhaust in the F344 rat and Ames assays.

Health Effects of Subchronic Exposure to Diesel–Water Emulsion Emission

The U.S. Environmental Protection Agency (EPA) National Ambient Air Quality Standards for ozone and particulate matter are requiring urban nonattainment areas to implement pollution-reduction strategies for anthropogenic source emissions. A type of fuel shown to decrease combustion emissions components versus traditional diesel fuels is the diesel–water emulsion. The Lubrizol Corporation in conjunction with Lovelace Respiratory Research Institute and several subcontracting laboratories recently conducted a rodent health assessment of inhaled combustion emissions of PuriNOx diesel fuel emulsion. Combustion emissions from either of two 2001 model Cummins 5.9-L ISB engines were diluted with charcoal-filtered air to exposure concentrations of 100, 200, and 400 μ g total particulate matter/m3. The engines were operated on a continuously repeating, heavy-duty certification cycle (U.S. Code of Federal Regulations, Title 40, Chapter I) using Rotella-T 15W-40 engine oil. Nitrogen oxide and particulate matter were reduced when engines were operated on PuriNOx versus California Air Resources Board diesel fuel under these conditions. Male and female F344 rats were housed in Hazleton H2000 exposure chambers and exposed to exhaust atmospheres 6 h/day, 5 days/wk for the first 11 wk and 7 days/wk threafter. Exposures ranged from 58 to 70 days, depending on the treatment group. Indicators of general toxicity (body weight, organ weight, clinical pathology, and histopathology), neurotoxicity (glial fibrillary acidic protein assay), genotoxicity (Ames assay, micronucleus, sister chromatid exchange), and reproduction and development were measured. Overall, effects observed were mild. Emulsion combustion emissions were not associated with neurotoxicity, reproductive/developmental toxicity, or in vivo genotoxicity. Small decreases in serum cholesterol and small increases in platelet values in some groups of exposed animals were observed. Particulate matter accumulation within alveolar macrophages was evident in all exposure groups. These findings are consistent with normal physiological responses to particle inhalation. Other statistically significant effects were present in some measured parameters of other exposed groups but were not clearly attributed to emissions exposure. Positive mutagenic responses in several strains of Salmonella typhimurium were observed subsequent to treatment with emulsion emissions subfractions. Based on the cholesterol and platelet results, it can be concluded that the 100-μ g/m3 exposure level was the no-observed-effect level. In general, biological findings in diesel emulsion emission-exposed animals and bacteria were consistent with exposure to petroleum diesel exhaust in the F344 rat and Ames assays.

Competitive Surface Interactions of Critical Additives with Piston Ring/Cylinder Liner Components under Lubricated Breaking-In conditions

Using a commercial mineral based API SJ/SAE 5W-30 engine oil. a series of breaking-in friction experiments employing a reciprocating tribotester was conducted under simulated engine condition with actual gasoline engine piston rings (Cr-plated, Mo+NiCrBSi-coated and nitrided) and cast iron cylinder liner combinations. Elemental analyses by energy dispersive X-Ray spectroscopy (EDX) of the wear trucks indicate that the antiwear agent ZDTP display higher selectivity than tile Mg- and Ca-containing detergents toward the tribosurfaces of both rings and liners. In particular, the tribosurface activity of the cast iron cylinder liners reacting with ZDTP is higher than that of the mated piston ring tribosurfaces. The tribosurfaces of all the piston rings sliding against the same cast iron liners exhibit almost the same activity when they react with ZDTP. Stronger interaction occurs between the steel tribosurfaces and the non-metallic functional additive elements (S and P), whose hardness or softness as Lewis acids and Lewis bases can be tailored to produce desired interactions. It is suggested that the tribochemical activity of tribosurfaces, which relies on both the thermodynamic properties of the materials and the triboprocesses involved, plays a role in determining the characteristic surface interactions of functional additive elements. Presented at the 56th Annual Meeting in Orlando, Florida May 20–24, 2001